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Date:   Wed, 21 Oct 2020 14:49:46 +0200
From:   Joerg Roedel <joro@8bytes.org>
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     Joerg Roedel <jroedel@suse.de>, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Kees Cook <keescook@chromium.org>,
        Martin Radev <martin.b.radev@gmail.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/5] x86/boot/compressed/64: Check SEV encryption in
 64-bit boot-path
Message-ID: <20201021124946.GA30514@8bytes.org>
References: <20201020121856.19427-1-joro@8bytes.org>
 <20201020121856.19427-4-joro@8bytes.org>
 <20201020141259.GC2996696@rani.riverdale.lan>
 <20201020154812.GB22179@suse.de>
 <20201020160428.GA3233355@rani.riverdale.lan>
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On Tue, Oct 20, 2020 at 12:04:28PM -0400, Arvind Sankar wrote:
> This is called from both assembly and C, but anyway, you're already
> assuming r10 and r11 can be clobbered safely, and you just took out the
> save/restores in set_sev_encryption_mask, which is actually called only
> from assembly.

Alright, maybe I was a bit too caucious. I changed the CR4 handling to
use %r8 and %r9 instead, which are also clobbered.

Regards,

	Joerg